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Understanding Sulfone Behavior in Palladium‐Catalyzed Domino Reactions with Aryl Iodides
Author(s) -
Alonso Inés,
Alcamí Manuel,
Mauleón Pablo,
Carretero Juan C.
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200600164
Subject(s) - aryl , domino , alkene , palladium , chemistry , catalysis , heck reaction , iodide , cascade reaction , sulfone , medicinal chemistry , combinatorial chemistry , organic chemistry , alkyl
Unlike traditionally used acyclic 1,2‐disubstituted alkenes, the reaction of α,β‐unsaturated phenyl sulfones with aryl iodides under Heck reaction conditions takes place mainly by means of a four‐component domino process, involving one unit of the alkene and three units of the aryl iodide, affording substituted 9‐phenylsulfonyl‐9,10‐dihydrophenanthrenes. We report here the results of a computational study on the mechanism of this domino arylation reaction. Based on these results we can explain why vinyl sulfones, unlike other electron‐deficient alkenes such as enones, preferentially follow this domino pathway instead of the usual Heck pathway. The key step is a CH activation process in which a five‐membered palladacycle is formed. The greater ability of vinyl sulfones, relative to enones, to reach the transition state that leads to the formation of the initial palladacycle makes the difference.